PLano convex lens


#1

I want to print a plano convex lens with a 6mm diameter and focal length of 25mm. Does anyone know where I could either get and .stl or find dimensions to make this lens.they are awfully expensive to buy.I want to use it to collimate an LED so it doesnt need to be perfect.

Carl


#3

I looked but no one has one.If I could just get the specs of the lens I could do it myself.I ordered a lens and I may try reverse engineering one from that.I did the lens project of the formlabs site a while back and made a pretty nice magnifying lens so I know I could get a clear enough lens-I just need the shape of the lens


#4

OK I got a formula.All I need now is the refractive index of formlabs clear resin.Is there a spec on this anywhere?

Carl


#5

The safety datasheet suggests that clear, when cured is a polymethacrylate. Then the refractive index of perspex i.e. 1.49 would be reasonable value.


#6

Thank you HansSpaan.I did find a post on the forum from the Formlabs team saying they think it is around 1.5. Now I know the curvature radius and can try making a lens.

Carl


#7

Edmund Optics makes the STP file available free for download. You will want a high fidelity STP to STL conversion for a smooth curvature surface so a free online converter may not be sufficient. ThorLabs lists the dimensions if you want to draw your own in your preferred CAD program and export the STL directly. How did your project go? I haven’t ordered clear resin yet but would be good to know for future reference how well the light diffusion was for your project.


#8

Thanks.it worked pretty well.There was some scatter of light, but I was using an RGB LED so it may have been related to the different wavelengths from the 3 separate LEDs.